fix(service-party-app): 修复 gRPC 客户端 TypeScript 类型错误

添加 ProtoPackage 接口定义 proto 包结构类型，避免类型推断错误

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/mpc-system/services/service-party-app/electron/modules/grpc-client.ts

@@ -6,6 +6,17 @@ import { EventEmitter } from 'events';
 // Proto 文件路径
 const PROTO_PATH = path.join(__dirname, '../../proto/message_router.proto');
 
+// 定义 proto 包结构类型
+interface ProtoPackage {
+  mpc?: {
+    router?: {
+      v1?: {
+        MessageRouter?: grpc.ServiceClientConstructor;
+      };
+    };
+  };
+}
+
 // 加载 Proto 定义
 const packageDefinition = protoLoader.loadSync(PROTO_PATH, {
   keepCase: true,
@@ -77,8 +88,8 @@ export class GrpcClient extends EventEmitter {
    */
   async connect(host: string, port: number): Promise<void> {
     return new Promise((resolve, reject) => {
-      const proto = grpc.loadPackageDefinition(packageDefinition) as Record<string, unknown>;
-      const MessageRouter = (proto.mpc?.router?.v1 as Record<string, unknown>)?.MessageRouter as grpc.ServiceClientConstructor;
+      const proto = grpc.loadPackageDefinition(packageDefinition) as ProtoPackage;
+      const MessageRouter = proto.mpc?.router?.v1?.MessageRouter;
 
       if (!MessageRouter) {
         reject(new Error('Failed to load MessageRouter service definition'));